Control of an excavation machine can be a difficult task to perform productively and efficiently, without causing operator fatigue. Such control can require years of experience and a high level of skill that not all operators posses. In order to ensure optimum performance of an excavation machine, even with inexperienced or low-skill operators, auto-dig systems are commonly utilized. Auto-dig systems automate many of the repetitive operations normally performed by a human operator.
A typical cycle for an excavation machine includes a dig segment, a swing-to-truck segment, a dump segment, and a swing-to-trench segment. Some of these segments are best performed by an operator, while others can be performed autonomously to reduce the fatigue of the operator and/or to reduce the skill or experience level that an operator must posses. For example, the dig and dump segments are generally best performed by a human operator, while the swinging segments can be performed autonomously or semi-autonomously. In order for an auto-dig system to benefit an operator, actuation of the system should be simple and cause little interruption in the excavation cycle.
One example of an auto-dig system is disclosed in U.S. Pat. No. 4,377,043 (the '043 patent) issued to Inui et al. on Mar. 22, 1983. The '043 patent discloses a semi-automatic hydraulic excavator capable of automatically controlling arm and bucket angles when bringing a bucket back to an original excavation posture after completion of a dumping step. The semi-automatic hydraulic excavator includes a manual-auto change over switch. When this switch is activated after the dumping step has been completed, and when an operator is controlling a boom cylinder to return the bucket to an excavation location (i.e., to within a trench), an arm cylinder and a boom cylinder are automatically controlled to orient the bucket for the next digging step before the bucket reaches the excavation location. Thus, the boom cylinder (as well as a swing cylinder and a bucket opening cylinder) is manually controlled, while the bucket and arm cylinders are automatically controlled in response to movement of the boom cylinder. In this manner, manual control of the excavation machine is simplified.
Although the semi-automatic hydraulic excavator of the '043 patent may simplify manual control thereof, the benefit may be limited. That is, the operator may still be required to complete many tasks manually (e.g., boom lift and boom swing), even during the autonomous portion of the excavation cycle. And, because the operator must activate an additional switch during each cycle for the semi-autonomous control to be implemented, the excavation cycle may be periodically interrupted.
The disclosed control system is directed to overcoming one or more of the problems set forth above.